We will study the deposition and clearance of particles in normal subjects and in patients with chronic bronchitis, cystic fibrosis, and diffuse pulmonary fibrosis. In the studies of deposition, we will compare the distribution of the particles in the lungs with the regional distribution of inspired air. Studies will be performed using various patterns of respiration, particle sizes, and particle densities. The studies of mucociliary clearance will be performed using tagged particles. In these studies the effect of dry air, oxygen and carbon dioxide will be considered. Furthermore, other studies will take into consideration the effect of the pattern of breathing and the effect of cough on mucociliary clearance. Correlations will be carried out between clearance and viscoelastic properties of the sputum collected by bronchoscopy. We will cary out assessments of viscosity as well as measurements of the glycoproteins and total solids in the sputum. BIBLIOGRAPHIC REFERENCES: Hass, F. J., P. S. Lee, and R. V. Lourenco. Tagging of iron oxide particles with 99mTc for use in the study of deposition and clearance of aerosols. J. Nucl. Med. 17:122, 1976. Warner, P., B. V. Joshi, R. V. Lourenco, P. S. Lee, and F. J. Hass. Cessation of smoking; effect on tracheobronchial clearance (TBC) of inhaled particles. Clin. Res., 24:391A, 1976 (Presented at the National Meeting of the American Federation for Clinical Research, Atlantic City, New Jersey, May 1976).